1) The main nav color can be changed with followng code (add it to style2.css at the very bottom):

.nav li a strong{
color: #333;
}

.nav li a span{
color: #333;
}

Change the color as you like. You can also add a hover effext.

2+3) Have a look at this thread: http://www.kriesi.at/support/topic/cufon – it tells you how to add a ufon font. To adjust the headline color add following code to style.css (at the very bottom) and change the color value to your needs: